This invention relates to a photosensitive member containing a new azo pigment.
Known photosensitive materials for forming a photosensitive member include inorganic photoconductive materials such as selenium, cadmium sulfide or zinc oxide.
These photosensitive materials have many advantages such as low loss of charges in the dark, an electrical charge which can be rapidly dissipated with irradiation of light and the like. However, they have disadvantages. For example, a photosensitive member based on selenium is difficult to produce, has high production costs and is difficult to handle due to inadequate resistivity to heat or mechanical impact. A photosensitive member based on cadmium sulfide has defects such as its unstable sensitivity in a highly humid environment and loss of stability with time because of the deterioration of dyestuffs, added as a sensitizer, by corona charge and fading with exposure.
Many kinds of organic photoconductive materials such as polyvinylcarbazole and so on have been proposed. These organic photoconductive materials have superior film forming properties, are light in weight, etc., but inferior in sensitivity, durability and environmental stability compared to the aforementioned inorganic photoconductive materials.
Various studies and developments have been in progress to overcome the above noted defects and problems. A function-divided photosensitive member of a laminated or a dispersed type has been proposed, in which charge generating function and charge transporting function are divided by different layers or different dispersed materials. The function-divided photosensitive member can be a highly efficient photosenistive member in electrophotographic properties such as chargeability, sensitivity, residual potential, durability with respect to copy and repetition, because most adequate materials can be selected from various materials. Further, function-divided photosensitive members have high productivity and low costs, since they can be prepared by coating, and suitably selected charge generating materials can freely control a region of photosensitive wavelength. Illustrative examples of such charge generating materials are organic pigments or dyes such as phthalocyanine pigment, cyanine pigment, polycyclic quinone pigment, perylene pigment, perinone pigment, indigo dye, thioindigo dye, squarain compounds, etc., and inorganic materials such as selenium, selenium-arsenic, selenium-tellurium, cadmium sulfide, zinc oxide, amorphous silicon, etc.
However, such photosensitive members, which satisfy general static property requirements, are not produced easily, and more improved sensitivity is desired.